When a mixed solution of KOH and NaOH and a solution of HCl were placed across a membrane of lactone-containing polymer, poly (3-vinyl-1, 4-butyrolactone-co-acrylonitrile), the selective transport of Na⁺ and K⁺ was observed. The transport behavior was much affected by the H⁺ concentration and the selectivity (K⁺/Na⁺) varied above and below unity. The selectivity was larger than unity at a higher H⁺ concentration, and smaller than unity at a moderate H⁺ concentration. When a solution of HCl was added into one side of NaOH solutions (same concentrations) which were separated with the membrane, Na⁺ was concentrated in the HCl side and H⁺ was counter-transported. It was suggested that the degree of ring-opening of lactone moiety in the membrane (chemical factor) and the lyophilicity or the hydrophilicity of the membrane (physical factor) control the selectivity. A proton-pump mechanism was considered for the concentration of Na⁺.

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Formation of small holes in the membrane of polystyrene microcapsules (capsules) prepared by evaporating the organic solvent from the organic phase in (W/O) /W complex emulsions has been investigated by microscopic observation. The number of holes (1-10 μm in diameter) in the surface of the capsules apparently increased as the agitation rate of primary W/O emulsions increased from 500 rpm to 9000 rpm and the increase was remarkable for large capsules (300-400 μm in diameter). The release of encapsulated α-amylase from the capsules was also enhanced as the stirring rate of the primary emulsions increased. A number of fine bubbles were observed by optical microscopy in the capsule membranes and they were assumed to be formed from fine droplets (several micrometer diameter) produced in the primary emulsions by rapid stirring. The size and distribution of the bubbles in the membranes were similar to those of the holes in the surface of the capsules. Therefore, the holes in the capsule membranes were presumably formed at thin film parts which were around the droplets and were easily breaked by a slight change in experimental condition such as temperature in the microencapsulation process.

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A polyamide was prepared by condensation of trans-2, 5-dimethyl piperazine and terephthaloyl chloride in chloroform solution using triethylamine at 2°C. The number average molecular weight M_n of the polyamide was 1.7×10⁴. Formic acid and formic acid-chloroform mixture were used as casting solvents. The ultrafiltration performance of the membrane prepared from a HCOOH-CHCl₃ solution was more dependent upon gelation medium than upon polymer content in casting solution, solvent composition or evaporation period. The membrane with a water flux of 18l/m²hr (4kg/cm² at 20°C) was formed from a HCOOH-CHCl₃ solution and its structure was observed by a scanning electron microscope. The membrane had an anisotropic structure constructed with both a thin active layer of 0.9-1.2μm and a porous support layer of 40μm. The membrane formed from mixed solvent exhibited a high rejection for Cytochrome C, while the one from formic acid as solvent showed a little rejection. The membrane having a water flux of 5.8l/m²hr exhibited rejections of 99.4% for Cytochrome C and of 72.7% for Vitamin B₁₂. At 166l/m²hr water flux level, the rejections for Hemoglobin, Cytochrome C, and Vitamin B₁₂ were 95.6, 79.4, and 38.8%, respectively.

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It was demonstrated that a liquid ion-exchange membrane (magnesium oleate+ 1-decanol) simulated the electrochemical features of the surface membrane of true slime mold Physarum polycephalum which were closely related to its recognition process. The features simulated were (1) initial (∂E/∂ log C) values were ca. 20 mV irrespective of number of charges of cations z, where E and C are the electromotive force and concentration respectively, (2) C_th (the minimum concentration of each chemical substance required to induce an appreciable change in the membrane potential or in the case of the mold, equivalent to the threshold concentration for chemotaxis) decreased with z^-6, and (3) (∂ log C_th/∂T) values were constant irrespective of kinds of chemical substances applied. This indicated that so far as the membrane phenomena were concerned in which the electrostatic force was of predominance, the surface membrane and the liquid ion-exchange membrane behaved in the same manner. Present results also suggested that the electrochemical properties of the surface membrane could be understood in terms of the interfacial phenomena at the cell surface extracellular solution interface.

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Permeation of water and water vapor through poly (L-leucine) (I) membrane was studied. Though the degree of hydration of I was about 1/3 of that of cellulose acetate (II) membrane, the water permeability of I was almost one order higher than that of II membrane. In comparison with poly (γ-methyl L-glutamate) (III) membrane, the degree of hydration was 1/2, and water permeability was almost the same. The activation energies determined from Arrhenius plots of hydraulic permeability and diffusion coefficient of water vapor are 2-2.5 times as high as that of viscous flow of water. The behavior was analysed by the free volume theory for mass transport, which showed that water was transported by diffusion of cluster of several water molecules through the loosely packed region between helices. Separation of water-soluble solutes through the homogeneous I membrane was examined. The rejection increased with the increase of molecular size of solute, and Bovine serum albumin was rejected in all the membranes. The solute rejection of I membrane was higher than that of III membrane, and this was considered to be due to hydrophobic nature of the side chain of I membrane.

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Permeability coefficient of oxygen has been examined for ethylene-inyl alcohol copolymer (EVA) films with different ethylene contents and its relation to the physical properties was discussed. The EVA films used in this study were obtained by melt-extrusion without any further heat-treatment or drawing. The logarithm of the permeability coefficients for EVA which contain ethylene over 30 mol% increased linearly with increasing ethylene content under a humidity below about 30%, although those of EVA with lower ethylene contents than 30 mol% deviated from this linearity by showing higher permeability coefficient than expected. These may be attributed to an accelerated molecular motion in the non-crystalline region of EVA caused by an adsorption of water between the molecular chains. Provided that the rate-determining process of the diffusion and permeation of oxygen would depend to a large extent on the formation of ‘hole’ the size of which is comparable to that of oxygen, the permeability coefficient for a randam copolymer was found to be expressed by the following equation:
ln P=V₁ln P₁+V₂ln P₂
where P and V are the permeability coefficient and volume fraction, respectively. Suffixes 1 and 2denote the components of random copolymer.

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A spiropyran compound, which undergoes photoisomerization, was incorporated to acetyl cellulose along with phosphatidylcholine in order to prepare a photo-responsive membrane. The transmembrane potential of the spiropyran-bound membrane was found to depend on visible and UV light irradiation. Phosphatidylcholine enhanced a great deal the photo-induced membrane potential change. The membrane potential changed in association with the photoisomerization of the bound-spiropyran. The role of phosphatidylcholine is discussed.

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Uniform membranes of various water contents were formed to obtain a basis for membrane design. Poly (methyl methacrylate) (I) and N-vinylpyrrolidone-methyl methacrylate copolymer (II) were used as examples of hydrophobic and hydrophilic membrane materials, respectively. Permeabilities were measured for water, NaCl and urea. Membrane of I showed much higher water permeability than II membrane at the same water content. But there was no significant difference between them in NaCl and urea permeabilities. The permeation through I membranes was elucidated using a capillary model, by taking account of tortuosity. The same model can also be applied to II membranes, assuming the existence of bound water on capillary walls.

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The utility of freeze-dried cellulose acetate membranes, which consist of a thin skin layer supported upon a more porous matrix substructure, was examined for separation of nitrogen-radioactive krypton 85. The high permeable and separative membranes were prepared by fixed freezed-drying of swollen membrane after evaporation of acetone for 4-6 minutes. The permeation rate of nitrogen was 10^-1 10^-3 (cc/cm²·sec·atm). Knudsen flow was predominant, since the permeation rate was inversely proportional to square root of molecular weight of gases. The influence of viscous flow was also observed by slight dependence on the pressure. The mean pore size was calculated by the equation of gas permeation in porous media. There exist fine pores of 30-40Å radii in the skin layer. The separation factor (dilution of Kr) was about 0.7 and the separation efficiency was 60%. The collision between different gas molecules (Present-de Bethunes' effect) and the influence of viscous flow depreciates the efficiency. The separation efficiency which was determined by the experiment coincided with the one predicted according to the Present-de Bethunes' equation, supposing that the pore size in skin layer was 10-25Å.

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An immunoresponsive membrane, which was prepared by immobilizing cardiolipin antigen, was applied to assemble an immunosensor for serological tests for syphilis. The sensor consists of the membrane potential measuring system, in which both surfaces of the immunoresponsive membrane are contacted with electrolyte solutions of the same concentration and an immunochemical reaction take place at one of the surfaces. The sensor exhibited an excellent performance in monitoring specifically the syphilis antibody in serum. The output of the sensor reached a steady state value by dipping 5 min, and increased with the increase in the antibody concentration and temperature. It ws concluded that the potential was generated due to an asymmetric charge distribution of the immunoresponsive membrane phase in association with an immunochemical reaction.

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